/* nag_lapacklin_dpftrf (f07wdc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.1, 2024.
 */

#include <nag.h>

int main(void) {
  /* Scalars */
  Integer exit_status = 0;
  Integer i, j, k, lar1, lar2, lenar, n, pdar, pda, q;
  /*  Arrays */
  double *ar = 0, *a = 0;
  char nag_enum_arg[40];
  /* NAG types */
  Nag_RFP_Store transr;
  Nag_UploType uplo;
  Nag_OrderType order;
  Nag_MatrixType matrix;
  NagError fail;

#ifdef NAG_COLUMN_MAJOR
  order = Nag_ColMajor;
#define AR(I, J) ar[J * pdar + I]
#else
  order = Nag_RowMajor;
#define AR(I, J) ar[I * pdar + J]
#endif

  INIT_FAIL(fail);

  printf("nag_lapacklin_dpftrf (f07wdc) Example Program Results\n");
  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%" NAG_IFMT "", &n);
  scanf("%39s", nag_enum_arg);
  uplo = (Nag_UploType)nag_enum_name_to_value(nag_enum_arg);
  scanf("%39s%*[^\n]", nag_enum_arg);
  transr = (Nag_RFP_Store)nag_enum_name_to_value(nag_enum_arg);

  lenar = (n * (n + 1)) / 2;
  pda = n;
  if (!(ar = NAG_ALLOC(lenar, double)) || !(a = NAG_ALLOC(pda * n, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Setup dimensions for RFP array ar. */
  k = n / 2;
  q = n - k;
  if (transr == Nag_RFP_Normal) {
    lar1 = 2 * k + 1;
    lar2 = q;
  } else {
    lar1 = q;
    lar2 = 2 * k + 1;
  }
  if (order == Nag_RowMajor) {
    pdar = lar2;
  } else {
    pdar = lar1;
  }
  /* Read matrix into RFP array ar. */
  for (i = 0; i < lar1; i++) {
    for (j = 0; j < lar2; j++) {
      scanf("%lf ", &AR(i, j));
    }
  }

  /* Factorize A using nag_lapacklin_dpftrf (f07wdc) which performs a
   * Cholesky factorization of real symmetric positive definite matrix in
   * Rectangular Full Packed format.
   */
  nag_lapacklin_dpftrf(order, transr, uplo, n, ar, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dpftrf (f07wdc)\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }
  printf("\n");

  /* Convert factor to full array form for printing using nag_matop_dtfttr
   * (f01vgc). Copies a real triangular matrix from Rectangular Full Packed
   * format to full matrix format
   */
  nag_matop_dtfttr(order, transr, uplo, n, ar, a, pda, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_matop_dtfttr (f01vgc)\n%s\n", fail.message);
    exit_status = 2;
    goto END;
  }

  matrix = (uplo == Nag_Lower ? Nag_LowerMatrix : Nag_UpperMatrix);
  /* nag_file_print_matrix_real_gen (x04cac).
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  nag_file_print_matrix_real_gen(order, matrix, Nag_NonUnitDiag, n, n, a, pda,
                                 "Factor", 0, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_real_gen (x04cac)\n%s\n",
           fail.message);
    exit_status = 3;
  }

END:
  NAG_FREE(ar);
  NAG_FREE(a);
  return exit_status;
}